OCELP is the use of code table vector quantization of the difference signal, and according to the degree of speech activation to produce a variable output rate signal. This encoding method is considered to be the most efficient encoding technology at present, and greatly improves the capacity of the system under the premise of ensuring better speech quality. The OCELP vocoder has sequences at 8kbit\/s and 13kbit\/s rates. The 8kbit\/s sequence is variable from 1.2kbit\/s to 9.6kbit\/s, and the 13kbit\/s sequence is variable from 1.8kbit\/s to 14.4kbit\/s.
SEVRC encoder is the latest encoding method, and also has the characteristics of large capacity of 8kbit\/s vocoder, and the voice quality has also been significantly improved.